// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_SURFACES_SURFACE_REFERENCE_MANAGER_H_
#define CC_SURFACES_SURFACE_REFERENCE_MANAGER_H_

namespace cc {

class SurfaceId;

// Interface to manage surface references.
class SurfaceReferenceManager {
public:
    // Returns the top level root SurfaceId. Surfaces that are not reachable
    // from the top level root may be garbage collected. It will not be a valid
    // SurfaceId and will never correspond to a surface.
    virtual const SurfaceId& GetRootSurfaceId() const = 0;

    // Adds a reference from a parent surface to a child surface. Any surface
    // embedding a child surface should have a reference added so that the child
    // surface is not garbage collected until after the parent surface.
    virtual void AddSurfaceReference(const SurfaceId& parent_id,
        const SurfaceId& child_id)
        = 0;

    // Removes a reference from a parent surface to a child surface.
    virtual void RemoveSurfaceReference(const SurfaceId& parent_id,
        const SurfaceId& child_id)
        = 0;

    // Returns the number of surfaces that have references to |surface_id|. When
    // the count is zero nothing is referencing the surface and it may be garbage
    // collected.
    virtual size_t GetSurfaceReferenceCount(
        const SurfaceId& surface_id) const = 0;

    // Returns the number of surfaces that |surface_id| has references to.
    virtual size_t GetReferencedSurfaceCount(
        const SurfaceId& surface_id) const = 0;

protected:
    virtual ~SurfaceReferenceManager() { }
};

} // namespace cc

#endif // CC_SURFACES_SURFACE_REFERENCE_MANAGER_H_
